Radio frequency system and password management method in radio frequency system

ABSTRACT

A radio frequency system and a password management method applied to a storage device of the radio frequency system are provided, in which a first access password is stored for deciding whether to permit access to information and a first changed password. The first changed password, a second access password, and a second changed password are received, and the first access password is changed to the second access password, and the first changed password is changed to the second changed password. Accordingly, information access authority in the storage device and a password change authority can be exclusively transferred according to the transfer of management of the storage device, and information leakage caused by a previous manager&#39;s password leakage or a third person&#39;s password leakage can be prevented.

This application claims the benefit under 35 U.S.C. § 119(a) of KoreanPatent Application No. 2005-83172, filed Sep. 7, 2005, in the KoreanIntellectual Property Office, the entire disclosure of which is herebyincorporated by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a radio frequency system and a passwordmanagement method in the radio frequency system. More particularly, thepresent invention relates to a radio frequency system and a passwordmanagement method in the radio frequency system using two types ofpasswords.

2. Description of the Related Art

A radio frequency system includes at least one storage device and atleast one reader. Here, the storage device means a small-capacitystorage device such as a smart card and a radio frequency identification(RFID) tag.

The smart card is a storage device that has a high security, highstability, and a mass storage capability, and its internal memory can beused in a divided manner. The smart card can be applied to diversefields of services. Application fields using smart cards may includebanking/settlement/distribution, information communication and mobilecommunication, medical welfare, access control, self-inspection of ameter, traffic fee collection, city complex card, and the like, and willbe steadily extended in the future.

The RFID tag is a tag in the form of a thin plate that is typically readby an object in a non-contact manner through a radio signal. The RFIDtag can be used in diverse application fields such as physicaldistribution, traffic, security, safety, and the like. Applicationservices using the RFID tag may include a burglarproof device in ashopping center, security system such as speaking drugs for a blindperson, forgery prevention device, animal tracking, vehicle safetydevice, private entrance/exit and access permission device, automaticfee collection system, production management, transport containerfreight tracking system, and the like. Also, the reader is a device thatreads stored information by accessing a storage device as describedabove.

Here, the storage device requires the control of access and use ofinformation stored in the storage device. That is, if access toinformation stored in the storage device is requested by an externalreader, the storage device confirms whether an access authority for theinformation stored in the storage device exists in the reader that hasrequested the access, through the confirmation of the passwordtransmitted from the reader.

Typically, the reader transmits a password required for accessingspecified information to a storage device, and decides whether to permitaccess to the specified information of the reader through a process forconfirming whether the transmitted password coincides with the passwordstored in the storage device.

However, as described above, the storage device may be a tag, which maybe attached to a product that is circulated in the market. In this case,the corresponding product may be managed by different managers accordingto distribution stages and the respective managers attempt to access thestorage device attached to the product through readers held by therespective managers.

According to a method for providing an authority to access informationin a storage device to managers at respective distribution stages, apassword for accessing information in the storage device can be sharedby the respective managers. In this case, however, the correspondingpassword may leak. Also, previous managers who have no authority tomanage the product any more can still access the information in thestorage device by the previously allocated password.

Accordingly, there is a need for an improved radio frequency system thatincludes a password management method for accessing information in astorage device and preventing password leaks.

SUMMARY OF THE INVENTION

An aspect of exemplary embodiments of the present invention is toaddress at least the above problems and/or disadvantages and to provideat least the advantages described below. Accordingly, an aspect ofexemplary embodiments of the present invention is to provide a radiofrequency system and a password management method in the radio frequencysystem using two types of passwords.

The foregoing and other objects and advantages are implemented realizedby providing a password management method in a radio frequency systemapplied to a storage device of the radio frequency system for storing afirst access password that decides whether to permit access toinformation and a first changed password, according to an exemplaryembodiment of the present invention, in which the first changedpassword, a second access password, and a second changed password isreceived when changing a password of the storage device is required dueto a change of ownership of the storage device and the like; and thefirst access password is changed to the second access password, and thefirst changed password is changed to the second changed password.

In an exemplary implementation, the access to the information stored inthe storage device is permitted when the second access password isreceived after the password change.

According to another aspect of exemplary embodiments of the presentinvention, there is provided a storage device in a radio frequencysystem for storing a first access password that decides whether topermit access to information and a first changed password, in which areceiving unit receives the first changed password, a second accesspassword, and a second changed password when changing a password of thestorage device is required due to a change of ownership of the storagedevice and the like; and a password management unit changes the firstaccess password to the second access password, and the first changedpassword to the second changed password when the receiving unit receivesthe first changed password, the second access password, and the secondchanged password.

In an exemplary implementation, an access decision unit permits theaccess to the information stored in the storage device itself when thesecond access password is received after the password change.

According to still another aspect of exemplary embodiments of thepresent invention, there is provided a radio frequency system that usesa first access password that decides whether to permit access toinformation and a first changed password, in which a reader transmitsthe first changed password, a second access password, and a secondchanged password to a storage unit when changing a password of thestorage device is required due to a change of ownership of the storagedevice and the like; and the storage device changes the first accesspassword to the second access password, and the first changed passwordto the second changed password when the first changed password, thesecond access password, and the second changed password are receivedfrom the reader.

In an exemplary implementation, the storage device may permit access tothe information stored in the storage device when the second accesspassword is received after the password change.

According to still another aspect of exemplary embodiments of thepresent invention, there is provided a password management method in aradio frequency system, applied to a reader of the radio frequencysystem that uses a first access password for deciding whether to permitaccess to information and a first changed password, in which a serialnumber of the storage device is received, the serial number of thestorage device is transmitted to a directory server which stores auniform resource locator (URL) of an information server that storesinformation corresponding to the serial number, the first accesspassword, and the first changed password, the URL of the informationserver is received, which stores the information corresponding to theserial number, from the directory server, the first changed password, asecond access password, and a second changed password is transmittedusing the URL, and the information server changes the first accesspassword to the second access password, and the first changed passwordto the second changed password.

In an exemplary implementation, the serial number and the second accesspassword is transmitted after the password change, using the URL, andaccess permission to the information is received corresponding to theserial number.

In another exemplary implementation, the transmitting of the serialnumber and the second access password using the URL may comprisetransmitting an access request signal to the information server andreceiving a random number, and transmitting the serial number and avalue obtained by substituting the random number and the first accesspassword in a one-way hash function to the information server.

In still another exemplary implementation, the transmitting of theserial number and the second access password using the URL may comprisetransmitting an access request signal and the serial number to theinformation server and receiving a random number, and transmitting avalue obtained by substituting the random number and the first accesspassword in a one-way hash function to the information server.

In an exemplary implementation, the transmitting of the serial numberand the first access password using the URL may comprise transmittingthe serial number, a transmission time, and a value obtained bysubstituting the serial number, the transmission time, and the firstaccess password in a one-way hash function to the information server.

In a further exemplary implementation, the transmitting of the firstchanged password, the second access password, and the second changedpassword may comprise transmitting a password change request signal tothe information server and receiving a random number, transmitting theserial number and a value obtained by substituting the random number andthe first changed password in a one-way hash function, and transmittingthe second access password and the second changed password.

According to still another aspect of exemplary embodiments of thepresent invention, there is provided a radio frequency system thatincludes an information server, at least one reader, and at least onestorage device, and uses a first access password for deciding whether topermit access to information and a second changed password, in which areceiving unit receives a serial number of the storage device, and atransmitting unit transmits the serial number to a directory serverwhich stores a uniform resource locator (URL) of an information serverthat stores information corresponding to the serial number, the firstaccess password, and a first changed password, wherein as the receivingunit receives the URL of the information server, which stores theinformation corresponding to the serial number, from the directoryserver, the transmitting unit transmits the serial number, the firstchanged password, a second access password, and the second changedpassword to the information server using the URL when it is required tochange a password of the storage device due to a change of ownership ofthe storage device, and the information server changes the first accesspassword to the second access password, and changes the first changedpassword to the second changed password.

In an exemplary implementation, the transmitting unit may transmit anaccess request signal to the information server, the receiving unit mayreceive a random number, and the transmitting unit may transmit theserial number and a value obtained by substituting the random number andthe first access password in a one-way hash function to the informationserver.

In another exemplary implementation, the transmitting unit may transmitan access request signal and the serial number to the informationserver, the receiving unit may receive a random number, and thetransmitting unit may transmit a value obtained by substituting therandom number and the first access password in a one-way hash functionto the information server.

In still another exemplary implementation, the transmitting unit maytransmit the serial number, a transmission time, and a value obtained bysubstituting the serial number, the transmission time, and the firstaccess password in a one-way hash function to the information server.

According to still another aspect of exemplary embodiments of thepresent invention, there is provided a password management method in aradio frequency system that includes at least one reader, at least onestorage device, and an information server which stores informationcorresponding to a serial number of the storage device, a first accesspassword, and a first changed password, in which comprises the serialnumber, the first changed password, a second changed password, and asecond access password are received when changing a password of thestorage device is required due to a change of ownership of the storagedevice and the like; and the first access password is changed to thesecond access password, and the first changed password is changed to thesecond changed password.

In an exemplary implementation, the serial number and the second accesspassword are received after the password change, and access toinformation corresponding to the serial number is permitted.

In another exemplary implementation, an access request signal isreceived and a random number is transmitted, and the serial number and avalue obtained by substituting the random number and the second accesspassword in a one-way hash function are received.

In still another exemplary implementation, an access request signal andthe serial number are received, and a random number is transmitted, anda value obtained by substituting the random number and the second accesspassword in a one-way hash function are received.

In a further exemplary implementation, the serial number, a transmissiontime, and a value obtained by substituting the serial number, thetransmission time, and the second access password in a one-way hashfunction are received.

According to still another aspect of exemplary embodiments of thepresent invention, there is provided a radio frequency system includingat least one reader, at least one storage device, and an informationserver that stores information corresponding to a serial number of thestorage device, a first access password, and a first changed password,in which comprises a transmitting/receiving unit receives the serialnumber, the first changed password, a second changed password, and asecond access password when changing a password of the storage device isrequired due to a change of ownership of the storage device and thelike; and a password management unit changes the first access passwordto the second access password and changing the first changed password tothe second changed password when the transmitting/receiving unitreceives the serial number, the first changed password, the secondchanged password, and the second access password.

In an exemplary implementation, the radio frequency system may furthercomprise an access decision unit for deciding whether to permit accessto information corresponding to the serial number when thetransmitting/receiving unit receives the serial number and the secondaccess password after the password change.

In another exemplary implementation, the transmitting/receiving unit mayreceive an access request signal, transmit a random number, and receivethe serial number and a value obtained by substituting the random numberand the second access password in a one-way hash function.

In still another exemplary implementation, the transmitting/receivingunit may receive an access request signal and the serial number,transmit a random number, and receive a value obtained by substitutingthe random number and the second access password in a one-way hashfunction.

In a further exemplary implementation, the transmitting/receiving unitmay receive the serial number, a transmission time, and a value obtainedby substituting the serial number, the transmission time, and the secondaccess password in a one-way hash function.

In an exemplary implementation, The transmitting/receiving unit mayreceive a password change request signal, transmit a random number,receive the serial number and a value obtained by substituting therandom number and the first changed password in a one-way hash function,and receive the second access password and the second changed password.

Other objects, advantages, and salient features of the invention willbecome apparent to those skilled in the art from the following detaileddescription, which, taken in conjunction with the annexed drawings,discloses exemplary embodiments of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other objects, features, and advantages of certainexemplary embodiments of the present invention will be more apparentfrom the following description taken in conjunction with theaccompanying drawings, in which:

FIG. 1A is a view explaining a password changing process in domain Aaccording to an exemplary embodiment of the present invention;

FIG. 1B is a view explaining an information access process in a storagedevice according to an exemplary embodiment of the present invention;

FIG. 1C is a view explaining a password changing process according to arequest of domain B according to an exemplary embodiment of the presentinvention;

FIG. 1D is a view explaining a password changing process in domain Baccording to an exemplary embodiment of the present invention;

FIG. 1E is a view explaining an information access process in a storagedevice according to an embodiment of the present invention;

FIG. 2 is a view illustrating a network structure according to anexemplary embodiment of the present invention;

FIGS. 3A to 3C are views explaining methods for requesting access to aninformation server on a network according to an exemplary embodiment ofthe present invention;

FIG. 4 is a view explaining a method for requesting a password change toan information server on a network according to an exemplary embodimentof the present invention;

FIGS. 5A to 5C are views explaining methods for requesting an URL to adirectory server on a network according to an exemplary embodiment ofthe present invention; and

FIG. 6 is a view explaining a method for requesting a password to adirectory server on a network according to an exemplary embodiment ofthe present invention.

Throughout the drawings, the same drawing reference numerals will beunderstood to refer to the same elements, features, and structures.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

The matters defined in the description such as a detailed constructionand elements are provided to assist in a comprehensive understanding ofthe embodiments of the invention. Accordingly, those of ordinary skillin the art will recognize that various changes and modifications of theembodiments described herein can be made without departing from thescope and spirit of the invention. Also, descriptions of well-knownfunctions and constructions are omitted for clarity and conciseness.

Embodiments of the present invention are characterized in that a personwho has taken over an access authority to information in a storagedevice uses two types of passwords in order to eliminate accesses of theprevious rightful persons.

The first type of password is used to receive access permission to theinformation in the storage device, and the second type of password isrequired for receiving an authentication of a right to change the firsttype of password as described above. If the authentication of an accessis made through the second type of password, it becomes possible tochange not only the first type of password, but also the second type ofpassword.

In the following description, the first type of password is called anaccess password (AP) and the second type of password is called a changedpassword (CP).

In an exemplary implementation, both the access password (AP) and thechanged password (CP) can be changed by the changed password (CP).

FIG. 1A is a view explaining a password changing process in domain Aaccording to an exemplary embodiment of the present invention.

In an exemplary implementation, a storage device 10 may be asmall-capacity storage device having calculation and communicationfunctions such as an RFID tag, and should store two or more passwords.

The storage device 10 according to an exemplary embodiment of thepresent invention includes a receiving unit for receiving passwords thatare transmitted from a reader, a password management unit for managingchange and storage of the passwords, and an access decision unit fordeciding whether to permit access to information.

The storage unit 10 authenticates the password transmitted from outside,identifies accessible information according to the password, andtransmits the requested information. In an exemplary implementation, thepassword stored in the storage device 10 should be protected from beingdirectly accessed from outside.

In the storage device 10, a first access password and a first changedpassword are stored as basic set values. Typically, the first accesspassword and the first changed password are set by a manufacturer in themanufacturing process of the storage device 10. The first accesspassword and the first changed password are transferred from themanufacturer to a manager 20 of domain A.

When the password of the storage device 10 intends to be changed, themanager 20 of domain A transmits the first changed password, a secondchanged password, and a second access password to the storage device 10using its reader, and commands a password change (S100).

The storage device 10 confirms whether the first changed password storedas a basic set value coincides with the transmitted first changedpassword. If the first changed password coincides with the transmittedfirst changed password, the storage device 10 changes the first changedpassword and the first access password to the second changed passwordand the second access password, respectively, to store the changedpasswords. In an exemplary implementation, the first changed passwordand the first access password that are previous passwords are deletedfrom the storage device 10.

In an exemplary embodiment of the present invention, the manager ofdomain A may be a seller of a product to which a storage device 10 isattached, and the authority to access data in the storage device 10 andchange the password is transferred from the manufacture to the managerof domain A through the above-described password changing process.

That is, through the above-described password changing process, themanufacturer becomes unable to access the data in the storage device 10or change the password.

It is preferable that the change of the password is performed in a safelocal place where its wiretapping is impossible. Thereafter, the manager20 of domain A can control whether to permit access to the storagedevice by providing the second access password required for accessingthe storage device 10 in accordance with the domain management policy.

FIG. 1B is a view explaining an information access process in a storagedevice according to an exemplary embodiment of the present invention. Areader 30 of domain B in FIG. 1B is a reader possessed by a member ofdomain B.

The manager 20 of domain A has provided the second access password thatis the changed password to the member of domain B. Thus, the member ofdomain B has stored the provided second access password in the reader 30of domain B. The storage of the provided password in the reader 30 ofthe domain B may be performed by an automatic input using an accesspassword transmitting device, or by a manual input of the member ofdomain B. In an automatic input, it is preferable to use a safecommunication channel such as a short-range infrared communication inwhich the wiretapping is difficult.

In an exemplary embodiment of the present invention, the manager 20 ofdomain A may be a seller of a product to which a storage device isattached, and the member of domain B may be a purchaser of the productto which the storage device is attached.

Referring to FIG. 1B, a process of accessing information in the storagedevice 10 according to an exemplary embodiment of the present inventionwill be explained. First, the reader 30 of domain B transmits the secondaccess password to the storage device 10 to request access to desiredinformation (S110).

In an exemplary implementation, the storage device 10 confirms whetherthe transmitted second access password coincides with the second accesspassword stored in the storage device itself. If the transmitted secondaccess password coincides with the stored second access password, thestorage device 10 transmits access information, which is permitted bythe transmitted second access password (S1120).

Although the reader 30 of domain B can access the information in thestorage device 10 through the above-described process, even the manager20 of domain A has the second access password. Thus, it is also possiblefor a third person who has received the second access password from themanager 20 of domain A, in addition to the manager 20 of domain A, toaccess the information in the storage device 10.

Also, since the manager 20 of domain A still has the second changedpassword, the second access password, which is the present password inthe storage device 10, may be changed to another password using thesecond changed password. Accordingly, the change may cause an accessauthority of the reader 30 of domain B to be divested.

In order to eliminate the above-described possibility and secure stableaccess to the information in the storage device 10 of the reader 30 ofdomain B, the following process will be required.

FIG. 1C is a view explaining a password changing process according to arequest of domain B according to an exemplary embodiment of the presentinvention.

Referring to FIG. 1C, the reader 30 of domain B transmits a thirdchanged password that will be used as a new password by the readeritself and a third access password to the reader of the manager 20 ofdomain A (S130), and then stores the changed passwords.

The transmission of the password in step S130 may be performed by anautomatic input using a password transmitting device. In an exemplaryimplementation, it is preferable to use a safe communication channelsuch as a short-range infrared communication in which the wiretapping isdifficult.

The manager 20 of domain A transmits the second changed password, thethird changed password, and the third access password to the storagedevice 10 using its reader, and then commands the password change(S140).

Then, the storage device 10 confirms whether the second changed passwordstored in the storage device itself coincides with the transmittedsecond changed password. If the stored second changed password coincideswith the transmitted second changed password, the storage device 10changes the second change password and the second access password to thethird changed password and the third access password, respectively, tostore the changed passwords. In an exemplary implementation, the secondchanged password and the second access password, which are the previouspasswords, are deleted from the storage device 10.

In an exemplary embodiment of the present invention, the manager 20 ofdomain A should not store the third changed password and the thirdaccess password, and should not expose the passwords to outside.

Through the above-described steps S130 and S140, the reader 30 of domainB secures the exclusive password change and access authorities withrespect to the storage device 10.

In an exemplary embodiment of the present invention, where a member ofdomain B who possesses the reader 30 of the domain B decides that it isrequired to change the password (due to the exposure of the password tooutside and the like), he/she may perform the following passwordchanging process using the third changed password.

FIG. 1D is a view explaining a password changing process in domain Baccording to an exemplary embodiment of the present invention. Referringto FIG. 1D, the domain B reader 30 transmits the third changed password,a fourth changed password and a fourth access password to the storagedevice 10, and commands the password change (S150).

Then, the storage device 10 confirms whether the third changed passwordstored in the storage device itself coincides with the transmitted thirdchanged password. If the stored third changed password coincides withthe transmitted third changed password, the storage device 10 changesthe third change password and the third access password to the fourthchanged password and the fourth access password, respectively, to storethe changed passwords. In this case, the third changed password and thethird access password, which are the previous passwords, are deletedfrom the storage device 10.

FIG. 1E is a view explaining an information access process in a storagedevice according to an exemplary embodiment of the present invention.

Referring to FIG. 1E, the information access process in the storagedevice according to an exemplary embodiment of the present inventionwill be explained. First, the reader 30 of domain B transmits the fourthaccess password to the storage device 10, and requests access to desiredinformation (S160).

In an exemplary implementation, the storage device 10 confirms whetherthe received fourth access password coincides with the fourth accesspassword stored in the storage device itself. If the received fourthaccess password coincides with the stored fourth access password, thestorage device 10 transmits access information, which is permitted bythe received fourth access password (S170).

On the other hand, in the radio frequency system according to anexemplary embodiment of the present invention, the storage device storesinformation on the storage device and information on a product where thestorage device is attached to the product. However, according to theenvironment and condition where the present invention is performed, itis required that the storage device is small. In an exemplaryimplementation, a large amount of information cannot be stored in thestorage device.

In an exemplary embodiment of the present invention, it may be requiredthat the storage device stores minimum information corresponding to itsserial number, and detailed information on the storage device and theproduct to which the storage device is attached is stored in an externalserver connected through the network.

FIG. 2 is a view illustrating a network structure according to anexemplary embodiment of the present invention.

The network structure according to an exemplary embodiment of thepresent invention includes a storage device 210, reader 230, objectdirectory server 250, and object information server 270.

The storage device 210 stores its serial number, and transmits itsserial number to the reader 230.

The reader 230 receives the serial number of the storage device 210, andrequests access to information corresponding to the serial number to theinformation server 270. In an exemplary implementation, the reader 230includes a receiving unit for receiving information signals from thestorage device 210, the directory server 250, and the information server270, and a transmitting unit for transmitting signals to the storagedevice 210, the directory server 250, and the information server 270.

The information server 270 stores serial numbers of the storage devices210 and information corresponding to the serial numbers. The directoryserver 250 stores a uniform resource locator (URL) of the informationserver 270 that stores the information corresponding to the serialnumbers of the storage devices 210.

In addition, if an access request is received from the reader 230, theinformation server 270 stores access passwords and changed passwordsrequired for deciding whether to permit access to the informationcorresponding to the serial numbers of the respective storage devices210.

The information server 270 includes a transmitting/receiving unit forreceiving the request signal, serial number, and password from thereader, a password management unit for managing the change and storageof the passwords, and an access decision unit for deciding whether topermit access to the information corresponding to the serial number.

Referring to FIG. 2, the operation of the network construction accordingto an exemplary embodiment of the present invention will be explained.First, the reader 230 receives the serial number from the storage device210 (S310), and stores the serial number in its storage unit (notillustrated). In an exemplary embodiment of the present invention,however, the serial number of the storage device 210 may be inputted bya user of the reader 230.

In order to access the information corresponding to the serial number ofthe storage device 210, the reader 230 transmits the serial number tothe directory server 250 that stores the URL of the information server270 corresponding to the respective serial number, and then receives theURL of the information server 270 that stores the informationcorresponding to the serial number (S320).

The directory server 250, which has received the serial number, confirmsthe URL of the information server 270 that stores the informationcorresponding to the serial number, and transmits the confirmed URL tothe reader 230 (S330).

The reader 230, which has received the URL, transmits the serial numberof the storage device 210 and the first access password required foraccessing the information corresponding to the serial number to theinformation server 270, and requests access to the correspondinginformation (S340). In an exemplary embodiment of the present invention,if the serial number corresponds to the first access password requiredfor accessing the information corresponding to the serial number in aone-to-one manner, the reader can request access to the correspondinginformation by the transmission of the first access password.

The information server 270 receives the serial number and the firstaccess password from the reader 230, confirms whether the first accesspassword corresponding to the serial number stored therein coincideswith the transmitted first access password. If the stored first accesspassword coincides with the transmitted first access password, theinformation server 270 transmits the information corresponding to theserial number to the reader 230 (S350).

However, since the directory server 250 and the information server 270according to an exemplary embodiment of the present invention areconstructed on the network, the serial number and the password may leakwhile they are transmitted to the reader 230. Accordingly, in order toprevent a third person's fraudulent use of the serial number and thepassword, it is preferable that the above-described step S340 isperformed by the following methods.

FIGS. 3A to 3C are views explaining methods for requesting access to aninformation server on a network according to an exemplary embodiment ofthe present invention. Hereinafter, the methods for requesting access toan information server on a network will be explained with reference toFIGS. 3A to 3C.

Referring to FIG. 3A, in transmitting the serial number of the storagedevice 230 and the first access password using the received URL, thereader 230 first transmits an access request signal to the informationserver 270 (S400).

The information server 270, which has received the access request signalfrom the reader 230, transmits a random number that has been randomlyextracted to the reader 230 (S405), and the reader 230 transmits theserial number and a value obtained by substituting the received randomnumber and the first access password in a one-way hash function to theinformation server (S410).

Here, the one-way hash function is a function for compressing an inputvalue of a certain length into an output value of a fixed length, andhas the following properties. In the one-way hash function, it isimpossible to calculate and obtain an input value with respect to agiven output value, and it is also impossible to calculate and findanother input value that provides the same output with respect to agiven input value. Also, in the one-way hash function, it is impossibleto calculate and find two different input values that provide the sameoutput value.

The one-way hash function that satisfies the above-described propertiesis one of important functions applied for data integrity,authentication, non-repudiation, and the like. In an exemplaryembodiment of the present invention, the reader 230 and the informationserver 270 will share the one-way hash function.

Then, the information server 270 authenticates the access to theinformation of the corresponding reader 230 through the transmittedone-way hash function value (S415), and transmits the informationcorresponding to the serial number, which has been requested by thereader 230 (S420).

Referring to FIG. 3B, in transmitting the serial number of the storagedevice 230 and the first access password using the received URL, thereader 230 first transmits an access request signal and the serialnumber of the storage device 210 to the information server 270 (S430).Accordingly, the information server 270 transmits a random number R thathas been randomly extracted to the reader (S435).

Then, the reader 230 transmits a value obtained by substituting thereceived random number and the first access password in theabove-described one-way hash function to the information server.Accordingly, the information server 270 authenticates the access to theinformation of the corresponding reader 230 through the transmittedone-way hash function value (S445), and transmits the informationcorresponding to the serial number, which has been requested by thereader 230 (S450).

Referring to FIG. 3C, in transmitting the serial number of the storagedevice 230 and the first access password using the received URL, thereader 230 may first transmit the serial number of the storage device210, present transmission time, and a value obtained by substituting theserial number, the transmission time, and the first access password inthe one-way hash function to the information server 270 (S460).

Accordingly, the information server 270 authenticates the access to theinformation of the corresponding reader 230 through the transmittedone-way hash function value (S470). Here, the transmission timetransmitted by the reader has the same role as the random number asillustrated in FIGS. 3A and 3B. Accordingly, whether to permit theaccess is decided. Then, the information server 270 transmits theinformation corresponding to the serial number, which has been requestedby the reader 230 (S480).

Referring again to FIG. 2, it may be required for the reader 230 tochange the password for the corresponding storage device 210. Therequired password change may be caused by the exposure of the password,and in changing the password, the reader 230 transmits the first changedpassword, the second access password, and the second changed password tothe information server 270 using the URL received from the directoryserver 250.

Then, the information server 270 confirms whether the received firstchanged password coincides with the first changed password stored in theinformation server itself. If the received first changed passwordcoincides with the stored first changed password, the information server270 stores the second access password and the second changed password.In an exemplary implementation, the first access password and the firstchanged password are deleted from the information server 270.

Then, in requesting access to the information server 270, the reader 230transmits the serial number and the changed second access password usingthe URL of the information server 270 (S340). Accordingly, theinformation server 270 receives the serial number and the second accesspassword from the reader 230, and confirms whether the second accesspassword corresponding to the serial number stored in the informationserver itself coincides with the received second access password. If thestored second access password coincides with the received second accesspassword, the information server transmits the information correspondingto the serial number to the reader 230 (S350).

However, since the directory server 250 and the information server 270according to an exemplary embodiment of the present invention areconstructed on the network, the serial number and the password may leakwhile they are transmitted to the reader 230. Accordingly, in order toprevent a third person's fraudulent use of the serial number and thepassword, it is preferable that the above-described password changingprocess is performed by the following methods.

FIG. 4 is a view explaining a method for requesting a password change toan information server on a network according to an exemplary embodimentof the present invention.

Referring to FIG. 4, in requesting the password change to theinformation server 270, the reader 210 first transmits a password changerequest signal to the information server 270 (S510). The informationserver 270 transmits a random number R that has been randomly extractedto the reader 230 (S520), and the reader 230, which has received therandom number, transmits the serial number of the corresponding storagedevice 210 and a value obtained by substituting the random number andthe first changed password in the one-way hash function to theinformation server (S530).

Then, the information server 270 authenticates the password changeauthority of the corresponding reader 230 through the received one-wayhash function (S540), and the reader 230 transmits the second changedpassword and the second access password that are changed passwords tothe information server 270 (S550). In an exemplary embodiment of thepresent invention, the reader 230 may transmit the second changedpassword and the second access password that are changed passwords tothe information server 270 after receiving the authentication signalfrom the information server 270 in step S540.

The information server 270 changes the stored passwords to the secondchanged password and the second access password (S560), and deletes thefirst changed password and the first access password.

In the network structure according to an exemplary embodiment of thepresent invention as described above with reference to FIGS. 3A to 3C,and FIG. 4, if the access request is received from the reader 230, theinformation server 270 stores the access password and the changedpassword required for deciding whether to permit access to theinformation corresponding to the serial number of the respective storagedevice 210.

In an exemplary embodiment of the present invention, however, thedirectory server 250 may store the access password and the changedpassword required for deciding whether to transmit the URL of theinformation server 270 that stores the information corresponding to theserial number of the respective storage device 210 when the URL requestis received from the reader 230.

The information server 270 according to an exemplary embodiment of thepresent invention includes a transmitting/receiving unit for receivingthe request signal, serial number, and password from the reader, apassword management unit for managing the change and storage of thepasswords, and a URL transmission decision unit for deciding whether totransmit the URL of the information server that stores the informationcorresponding to the serial number.

Referring again to FIG. 2, the operation of the network constructionaccording to an exemplary embodiment of the present invention will beexplained. First, the reader 230 receives the serial number from thestorage device 210 (S310), and stores the serial number in its storageunit (not illustrated). In an exemplary embodiment of the presentinvention, however, the serial number of the storage device 210 may beinputted by a user of the reader 230.

Then, in order to access the information corresponding to the serialnumber of the storage device 210, the reader 230 transmits the serialnumber and the first access password to the directory server 250 thatstores the URL of the information server 270, the first access password,and the first changed password, and then receives the URL of theinformation server 270 that stores the information corresponding to theserial number (S320).

In an exemplary embodiment of the present invention, if the serialnumber corresponds to the first access password required for receivingthe URL of the information server 270 that stores the informationcorresponding to the serial number in a one-to-one manner, the readercan request the transmission of the corresponding URL by thetransmission of the first access password.

The directory server 250 confirms whether the transmitted first accesspassword coincides with a pre-stored first access password. If thetransmitted first access password coincides with the pre-stored firstaccess password, the directory server 250 transmits the URL of theinformation server that stores the information corresponding to theserial number (S330).

The reader 230 transmits the serial number of the corresponding storagedevice 210 to the information server 270 using the received URL (S340).

The information server 270 transmits the information corresponding tothe received serial number to the reader 230 (S350).

However, since the directory server 250 and the information server 270according to an exemplary embodiment of the present invention areconstructed on the network, the serial number and the password may leakwhile they are transmitted to the reader 230. Accordingly, in order toprevent a third person's fraudulent use of the serial number and thepassword, it is preferable that the above-described step S320 isperformed by the following methods.

FIGS. 5A to 5C are views explaining methods for requesting a URL to adirectory server on a network according to an exemplary embodiment ofthe present invention. Hereinafter, the methods for requesting a URL tothe directory server on the network will be explained with reference toFIGS. 5A to 5C.

Referring to FIG. 5A, in requesting the URL to the directory server 250,the reader 230 first transmits a URL request signal to the directoryserver 250 (S500).

The directory server 250, which has received the URL request signal fromthe reader 230, transmits a random number that has been randomlyextracted to the reader 230 (S505), and the reader 230 transmits theserial number and a value obtained by substituting the received randomnumber and the first access password in a one-way hash function to thedirectory server 250 (S510).

In an exemplary embodiment of the present invention, the reader 230 andthe directory server 250 will share the one-way hash function.

Then, the directory server 250 authenticates the access to theinformation of the corresponding reader 230 through the transmittedone-way hash function value (S515), and transmits the informationcorresponding to the serial number, which has been requested by thereader 230 (S520).

Referring to FIG. 5B, in requesting the URL to the directory server 250,the reader 230 first transmits a URL request signal and the serialnumber of the storage device 210 to the directory server 250 (S530).Accordingly, the directory server 250 transmits a random number R thathas been randomly extracted to the reader (S535).

Then, the reader 230 transmits a value obtained by substituting thereceived random number and the first access password in theabove-described one-way hash function to the directory server 250.Accordingly, the directory server 250 authenticates the access to theinformation of the corresponding reader 230 through the transmittedone-way hash function value (S545), and transmits the informationcorresponding to the serial number, which has been requested by thereader 230 (S550).

Referring to FIG. 5C, in requesting the URL to the directory server 250,the reader 230 may transmit the serial number of the storage device 210,the present transmission time, and a value obtained by substituting theserial number, the transmission time, and the first access password inthe one-way hash function to the directory server 250 (S560).

Accordingly, the directory server 250 authenticates the access to theinformation of the corresponding reader 230 through the transmittedone-way hash function value (S570). Here, the transmission timetransmitted by the reader has a similar role as the random numberillustrated in FIGS. 5A and 5B. Accordingly, whether to permit theaccess is decided. Then, the directory server 250 transmits theinformation corresponding to the serial number, which has been requestedby the reader 230 (S580).

Referring again to FIG. 2, it may be required for the reader 230 tochange the corresponding password. As described above, this may becaused by the exposure of the password. In changing the password, thereader 230 transmits the first changed password, the second accesspassword, and the second changed password to the directory server 250.

Then, the directory server 250 confirms whether the received firstchanged password coincides with the first changed password stored in thedirectory server. If the received first changed password coincides withthe stored first changed password, the directory server 250 stores thesecond access password and the second changed password. In this case,the first access password and the first changed password are deletedfrom the directory server 250.

Then, in requesting the URL to the directory server 250, the reader 230transmits the serial number and the changed second access password(S320). Accordingly, the directory server 250 receives the serial numberand the second access password from the reader 230, and confirms whetherthe second access password corresponding to the serial number stored inthe directory server itself coincides with the received second accesspassword. If the stored second access password coincides with thereceived second access password, the directory server transmits the URLof the information server 270 that stores the information correspondingto the serial number (S330).

The reader 230 transmits the serial number of the storage device 210 tothe information server 270 using the received URL (S340), and theinformation server 270, which has received the serial number, transmitsthe information corresponding to the serial number (S350).

However, since the directory server 250 and the information server 270according to an exemplary embodiment of the present invention areconstructed on the network, the serial number and the password may leakwhile they are transmitted to the reader 230. Accordingly, in order toprevent a third person's fraudulent use of the serial number and thepassword, it is preferable that the above-described password changingprocess is performed by the following method.

FIG. 6 is a view explaining a method for requesting a password to adirectory server on a network according to an exemplary embodiment ofthe present invention.

Referring to FIG. 6, in requesting the password change to the directoryserver 250, the reader 210 first transmits a password change requestsignal to the directory server 250 (S610). The directory server 250transmits a random number R that has been randomly extracted to thereader 230 (S620). The reader 230, which has received the random number,transmits the serial number of the corresponding storage device 210 anda value obtained by substituting the random number and the first changedpassword in the one-way hash function to the directory server (S630).

Then, the directory server 250 authenticates the password changeauthority of the corresponding reader 230 through the received one-wayhash function (S640), and the reader 230 transmits the second changedpassword and the second access password that are the changed passwordsto the directory server 250 (S650). In an exemplary embodiment of thepresent invention, the reader 230 may transmit the second changedpassword and the second access password that includes the changedpasswords to the directory server 250 after receiving the authenticationsignal from the directory server 250 in step S640.

The information server 270 changes the stored passwords to the secondchanged password and the second access password (S660), and deletes thefirst changed password and the first access password.

As described above, according to exemplary embodiments of the presentinvention, the information access authority in the storage device andthe password change authority can be exclusively transferred accordingto the transfer of management of the storage device, and the informationleakage caused by a previous manager's password leakage or a thirdperson's password leakage can be prevented.

While the invention has been shown and described with referent tocertain exemplary embodiments thereof, it will be understood by thoseskilled in the art that various changes in form and details may be madetherein without departing from the spirit and scope of the invention asdefined by the appended claims.

1. A password management method in a radio frequency system, applied toa storage device of the radio frequency system, the password managementmethod comprising the steps of: storing a first access password fordetermining whether to permit access to information and a first changedpassword; receiving the first changed password, a second accesspassword, and a second changed password; changing the first accesspassword to the second access password; and changing the first changedpassword to the second changed password.
 2. The password managementmethod as claimed in claim 1, further comprising permitting access toinformation stored in the storage device when the second access passwordis received after the password change.
 3. A storage device in a radiofrequency system, for storing a first access password for determiningwhether to permit access to information and a first changed password,the storage device comprising: a receiving unit for receiving the firstchanged password, a second access password, and a second changedpassword; and a password management unit for changing the first accesspassword to the second access password, and changing the first changedpassword to the second changed password when the receiving unit receivesthe first changed password, the second access password, and the secondchanged password.
 4. The storage device as claimed in claim 3, furthercomprising an access decision unit for permitting access to theinformation stored in the storage device when the second access passwordis received after the password change.
 5. A radio frequency system thatuses a first access password for determining whether to permit access toinformation and a first changed password, the radio frequency systemcomprising: a reader for transmitting the first changed password, asecond access password, and a second changed password to a storage unit;and the storage device for changing the first access password to thesecond access password, and changing the first changed password to thesecond changed password when the first changed password, the secondaccess password, and the second changed password are received from thereader.
 6. The radio frequency system as claimed in claim 5, wherein thestorage device permits access to the information stored in the storagedevice when the second access password is received after the passwordchange.
 7. A password management method in a radio frequency system,applied to a reader of the radio frequency system that uses a firstaccess password for determining whether to permit access to informationand a first changed password, the password management method comprising:receiving a serial number of a storage device; transmitting the serialnumber of the storage device to a directory server which stores auniform resource locator (URL) of an information server that storesinformation corresponding to the serial number, the first accesspassword, and the first changed password; receiving the URL of theinformation server from the directory server; transmitting the firstchanged password, a second access password, and a second changedpassword using the URL; and changing the first access password to thesecond access password, and the first changed password to the secondchanged password.
 8. The password management method as claimed in claim7, further comprising: transmitting the serial number and the secondaccess password after the password change using the URL; and receivingaccess permission to the information corresponding to the serial number.9. The password management method as claimed in claim 8, wherein thetransmitting of the serial number and the second access password usingthe URL, comprises: transmitting an access request signal to theinformation server and receiving a random number; and transmitting theserial number and a value obtained by substituting the random number andthe first access password in a one-way hash function to the informationserver.
 10. The password management method as claimed in claim 8,wherein the transmitting of the serial number and the second accesspassword using the URL, comprises: transmitting an access request signaland the serial number to the information server and receiving a randomnumber; and transmitting a value obtained by substituting the randomnumber and the first access password in a one-way hash function to theinformation server.
 11. The password management method as claimed inclaim 8, wherein the transmitting of the serial number and the firstaccess password using the URL comprises transmitting the serial number,a transmission time, and a value obtained by substituting the serialnumber, the transmission time, and the first access password in aone-way hash function, to the information server.
 12. The passwordmanagement method as claimed in claim 7, wherein the transmitting of thefirst changed password, the second access password, and the secondchanged password, comprises: transmitting a password change requestsignal to the information server and receiving a random number;transmitting the serial number and a value obtained by substituting therandom number and the first changed password in a one-way hash function;and transmitting the second access password and the second changedpassword.
 13. A radio frequency system using a first access password fordetermining whether to permit access to information and a second changedpassword, the radio frequency system comprising: at least one reader; atleast one storage device; a receiving unit for receiving a serial numberof the storage device; and a transmitting unit for transmitting theserial number to a directory server which stores a uniform resourcelocator (URL) of an information server that stores informationcorresponding to the serial number, the first access password, and afirst changed password; wherein as the receiving unit receives the URLof the information server, which stores the information corresponding tothe serial number, from the directory server, the transmitting unittransmits the serial number, the first changed password, a second accesspassword, and the second changed password to the information serverusing the URL; and the information server changes the first accesspassword to the second access password, and the first changed passwordto the second changed password.
 14. The radio frequency system asclaimed in claim 13, wherein the transmitting unit transmits an accessrequest signal to the information server, the receiving unit receives arandom number, and the transmitting unit transmits the serial number anda value obtained by substituting the random number and the first accesspassword in a one-way hash function to the information server.
 15. Theradio frequency system as claimed in claim 13, wherein the transmittingunit transmits an access request signal and the serial number to theinformation server, the receiving unit receives a random number, and thetransmitting unit transmits a value obtained by substituting the randomnumber and the first access password in a one-way hash function to theinformation server.
 16. The radio frequency system as claimed in claim13, wherein the transmitting unit transmits the serial number, atransmission time, and a value obtained by substituting the serialnumber, the transmission time, and the first access password in aone-way hash function to the information server.
 17. A passwordmanagement method in a radio frequency system comprising at least of onereader, one storage device, and an information server for storinginformation corresponding to a serial number of the storage device, afirst access password, and a first changed password, the passwordmanagement method comprising: receiving a serial number, a first changedpassword, a second changed password, and a second access password; andchanging the first access password to the second access password, andthe first changed password to the second changed password.
 18. Thepassword management method as claimed in claim 17, further comprising:receiving the serial number and the second access password after thepassword change; and permitting access to information corresponding tothe serial number.
 19. The password management method as claimed inclaim 18, wherein the receiving of the serial number and the secondaccess password comprises: receiving an access request signal andtransmitting a random number; and receiving the serial number and avalue obtained by substituting the random number and the second accesspassword in a one-way hash function.
 20. The password management methodas claimed in claim 18, wherein the receiving the serial number and thesecond access password comprise: receiving an access request signal andthe serial number and transmitting a random number; and receiving avalue obtained by substituting the random number and the second accesspassword in a one-way hash function.
 21. The password management methodas claimed in claim 18, wherein the receiving of the serial number andthe second access password comprises receiving the serial number, atransmission time, and a value obtained by substituting the serialnumber, the transmission time, and the second access password in aone-way hash function.
 22. A radio frequency system comprising at leastone reader, at least one storage device, and an information server thatstores information corresponding to a serial number of the storagedevice, a first access password, and a first changed password, the radiofrequency system comprising: a transmitting and receiving unit forreceiving the serial number, the first changed password, a secondchanged password, and a second access password; and a passwordmanagement unit for changing the first access password to the secondaccess password and changing the first changed password to the secondchanged password when the transmitting and receiving unit receives theserial number, the first changed password, the second changed password,and the second access password.
 23. The radio frequency system asclaimed in claim 22, further comprising an access decision unit fordetermining whether to permit access to information corresponding to theserial number when the transmitting and receiving unit receives theserial number and the second access password after the password change.24. The radio frequency system as claimed in claim 23, wherein thetransmitting and receiving unit receives an access request signal,transmits a random number, and receives the serial number and a valueobtained by substituting the random number and the second accesspassword in a one-way hash function.
 25. The radio frequency system asclaimed in claim 23, wherein the transmitting and receiving unitreceives an access request signal and the serial number, transmits arandom number, and receives a value obtained by substituting the randomnumber and the second access password in a one-way hash function. 26.The radio frequency system as claimed in claim 23, wherein thetransmitting and receiving unit receives the serial number, atransmission time, and a value obtained by substituting the serialnumber, the transmission time, and the second access password in aone-way hash function.
 27. The radio frequency system as claimed inclaim 22, wherein the transmitting and receiving unit receives apassword change request signal, transmits a random number, receives theserial number and a value obtained by substituting the random number andthe first changed password in a one-way hash function, and receives thesecond access password and the second changed password.